Energy conversion system for a vehicle

ABSTRACT

An energy conversion system transfers energy between an energy source, or storage unit, and an electric device via a first port and a second port and at least one of receives and provides energy via a third port.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of application Ser. No. 11/537,083,filed Sep. 29, 2006, now U.S. Pat. No. 8,232,669, which is herebyincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to energy conversion systems for vehicles.

2. Background Discussion

Direct current to direct current (DC/DC) buck, boost, or bi-directionalconverters may transfer energy between an energy source, or storageunit, e.g., a high-voltage battery, via a first port at a first voltageand an electric device, e.g., motor drive, via a second port at a secondvoltage higher than the first voltage.

A vehicle system may require energy to be transferred between severalenergy storage units and electric devices at differing voltages. SeveralDC/DC converters may be necessary to facilitate such energy transfer.

An energy conversion system is desired that can facilitate the transferof energy between one or more energy storage units and one or moreelectric devices at differing voltages.

SUMMARY OF THE INVENTION

In at least one embodiment, the invention takes the form of an energyconversion system for a vehicle. The system includes an energy source,or storage unit, an electric device, and an energy conversionarrangement. The arrangement transfers energy between the energy storageunit and the electric device via a first port and a second port. Thearrangement also at least one of receives and provides energy via athird port.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an energy conversion system in accordance with anembodiment of the invention.

FIG. 2 shows an energy conversion arrangement in accordance with anembodiment of the invention.

FIG. 3 shows an energy conversion arrangement in accordance with anembodiment of the invention.

FIG. 4 shows a transformer in accordance with an embodiment of theinvention.

FIG. 5 shows a transformer in accordance with an embodiment of theinvention.

FIG. 6 shows a transformer in accordance with an embodiment of theinvention.

FIGS. 7 a-7 d show circuits in accordance with embodiments of theinvention.

FIG. 8 shows an energy conversion arrangement in accordance with anembodiment of the invention.

FIG. 9 shows an energy conversion arrangement in accordance with anembodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIG. 1 shows energy conversion system 10 for vehicle 12. System 10includes energy sources, or storage units, 14, 15, energy conversionarrangement 16, and electric devices 18, 19. Arrangement 16 iselectrically connected with units 14, 15 and devices 18, 19. Arrangement16 may receive energy from or provide energy to units 14, 15, as will beexplained in detail below. Arrangement 16 may also receive energy fromor provide energy to devices 18, 19, as will be explained in detailbelow.

FIG. 2 shows an embodiment of arrangement 16. In this embodiment,arrangement 16 receives energy from unit 14 and provides energy todevice 18 and acts, inter alia, as a DC/DC boost converter.

Arrangement 16 includes capacitors 20, 22, switch 24, diode 26, andtransformer 28 as shown in FIG. 2. Switch 24 is an insulated gatebipolar transistor (IGBT). Switch 24, however, may be implemented in anysuitable fashion, such as with field effect transistors (FETs).Transformer 28 may be an isolated transformer or a non-isolatedtransformer, as will be explained in detail below.

Arrangement 16 also includes terminals 30, 31, 32. Terminal 31 is commonrelative to terminal 30 and terminal 32. Unit 14, capacitor 20, andtransformer 28 are electrically connected with terminal 30. Unit 14 andcapacitor 20 are also electrically connected with terminal 31. Terminal30 and terminal 31 are a port. Device 18 is electrically connected withterminal 31 and terminal 32. Terminal 31 and terminal 32 are a port. Thevoltage, Vy, at terminal 32 relative to terminal 31 is greater than thevoltage, Vx, at terminal 30 relative to terminal 31. Arrangement 16further includes node 33.

Arrangement 16 passes current between terminal 30 and terminal 32 in amanner typical of DC/DC boost converters through the selective openingand closing of switch 24, e.g., pulse width modulation. When switch 24is conducting, the current through transformer 28 increases therebyincreasing the energy stored in transformer 28. When switch 24 is notconducting, the energy stored in transformer 28 forces diode 26 toconduct thereby delivering current to terminal 32.

Arrangement 16 also includes one or more terminals 36, i.e., 36 a-36 n.Terminals 36 a-36 n are electrically connected to transformer 28, aswill be explained in detail below. Terminal 36 a may be electricallyconnected with unit 15. Terminal 36 b may be electrically connected withdevice 19. If transformer 28 is a non-isolated transformer, unit 15 anddevice 19 may share a common reference terminal, e.g., terminal 31.Terminal 31 and any of terminals 36 a-36 n may be a port. If transformer28 is an isolated transformer, unit 15 and device 19 may or may notshare a common reference terminal. Preferably, unit 15 and device 19would not share a common reference terminal if transformer 28 is anisolated transformer. Any two of terminals 36 a-36 n may be a port.

FIG. 3 shows an embodiment of arrangement 16. In this embodiment,arrangement 16 receives energy from device 18 and provides energy tounit 14 and acts, inter alia, as a DC/DC buck converter.

Arrangement 16 includes capacitors 20, 22, switch 24, diode 26, andtransformer 28. Switch 24 is an IGBT. Switch 24, however, may beimplemented in any suitable fashion, such as with FETs. Transformer 28may be an isolated transformer or a non-isolated transformer asexplained above. Arrangement 16 also includes terminals 30, 31, 32.Terminal 31 is common relative to terminal 30 and terminal 32. Unit 14,capacitor 20, and transformer 28 are electrically connected withterminal 30. Unit 14 and capacitor 20 are also electrically connectedwith terminal 31. Device 18 is electrically connected with terminal 31and terminal 32. The voltage, Vy, at terminal 32 relative to terminal 31is greater than the voltage, Vx, at terminal 30 relative to terminal 31.Arrangement 16 further includes node 33.

Arrangement 16 passes current between terminal 30 and terminal 32 in amanner typical of DC/DC buck converters through the selective openingand closing of switch 24, e.g., pulse width modulation. When switch 24is conducting, current flows from terminal 32 to terminal 30. Whenswitch 24 is not conducting, current flows from terminal 31 to terminal30.

Arrangement 16 also includes one or more terminals 36, i.e., 36 a-36 n.Terminals 36 are electrically connected to transformer 28 as will beexplained in detail below. Terminal 36 a may be electrically connectedwith unit 15. Terminal 36 b may be electrically connected with device19.

FIG. 4 shows an isolated version of transformer 28. This isolatedtransformer 28 includes primary winding 38 and secondary winding 40,both being wound around magnetic core 42. The transformer 28 may havemultiple mutually isolated secondary windings 40. Terminals 36 a-36 nhave voltages with no offset. The amplitude of the voltage differencebetween terminals 36 a and 36 x is less than the amplitude of thevoltage difference between terminals 36 a and 36 n. Current coming fromany of terminals 36 a-36 n may be rectified in any suitable fashion,such as with a full-wave rectifier or half-wave rectifier, as will beexplained in detail below.

FIG. 5 shows a non-isolated version of transformer 28. This non-isolatedtransformer 28 includes primary winding 44 wound around magnetic core46. Terminals 36 a-36 n have voltages, with respect to terminal 31 orany other common reference terminal, with offset. Terminal 30 may beconnected with any of terminals 36 a-36 n. Node 33 may be connected withany of terminals 36 a-36 n. Terminal 30 and node 33, however, may not beconnected to the same terminal. Current coming from any of terminals 36a-36 n may be rectified in any suitable fashion, such as with afull-wave rectifier or half-wave rectifier, as will be explained indetail below. This non-isolated transformer 28 may also include isolatedsecondary windings. Therefore, it may have non-isolated as well asisolated outputs.

FIG. 6 shows an isolated version of transformer 28. Switches 48, 50, 52,and 54 may be selectively opened or closed. If switch 54 is closed andswitches 48, 50, and 52 are open, secondary winding 40 is isolated fromprimary winding 38. It provides power to a load with galvanic isolationwith respect to the primary side. If secondary winding 40 is not used,it can be incorporated with primary winding 38 to increase the powerrating or inductance. For example, if switches 48, 50, and 54 are closedand switch 52 is open, primary winding 38 and secondary winding 40 areconnected in parallel, thus increasing the current rating of transformer28. If switches 50 and 52 are closed and switches 48 and 54 are open,primary winding 38 and secondary winding 40 are connected in series,thus increasing the inductance of transformer 28. Switches 48, 50, 52,and 54 may be implemented in any suitable fashion. In the embodiment ofFIG. 6, switches 48, 50, 52, and 54 are relays.

FIG. 7 a shows rectifier circuit 56 that may be used with transformer28. Circuit 56 includes diodes 58, 60 electrically connected, as shown,along with output terminals 62, 64. If the voltage at terminal 36 isgreater than the voltage at terminal 62, diode 58 will conduct. If thevoltage at terminal 36 is less than the voltage at terminal 64, diode 60will conduct.

FIG. 7 b shows rectifier circuit 66 that may be used in conjunction withtransformer 28. Circuit 66 includes diodes 68, 70, 72, and 74electrically connected as shown. Circuit 66 also includes terminals 76,78, 80, and 82. Terminal 76 and terminal 82 are a port. Terminal 78 andterminal 80 are another port. The ports do not share a common referenceterminal and they deliver two output voltages with different amplitudes.

FIG. 7 c shows rectifier circuit 84 that may be used in conjunction withtransformer 28. Circuit 84 includes diodes 86, 88, 90, and 92electrically connected as shown. Circuit 84 also includes terminals 94,96, and 98. Terminal 94 and terminal 98 are a port. Terminal 96 andterminal 98 are another port. The ports share common negative-sidereference terminal 98. The outputs of the ports are of the same polaritybut may have different output voltage amplitudes.

FIG. 7 d shows rectifier circuit 100 that may be used in conjunctionwith transformer 28. Circuit 100 includes diodes 102, 104, 106, and 108electrically connected as shown. Circuit 100 also includes terminals110, 114, and 116. Terminal 114 and terminal 110 are a port. Terminal116 and terminal 110 are another port. The ports share commonpositive-side reference terminal 110. The outputs of the ports are ofthe same polarity but may have different output voltage amplitudes.

FIG. 8 shows an embodiment of arrangement 16. This embodiment includescapacitors 118, 120, terminals 122, 123, 124, node 126, diodes 128, 130,active switches 132, 134, and non-isolated transformer 136. In thisconfiguration, arrangement 16 can act as either a buck or boostconverter. If switch 132 is disabled, arrangement 16 acts, inter alia,as a boost converter. If switch 134 is disabled, arrangement 16 acts,inter alia, as a buck converter. The voltage at terminal 122 is lessthan the voltage at terminal 124 relative to terminal 123.

Non-isolated transformer 136 includes terminals 138, e.g., 138 a-138 j.Terminals 140, e.g., 140 a-140 h, and terminals 142, e.g., 142 a-142 h,are also shown. Other embodiments may have more or less terminals. Thediodes may or may not be included.

If arrangement 16 acts as a buck converter, i.e., switch 134 isdisabled, the voltage at terminals 142 g-142 h is less than the voltageat terminal 122, the voltage at terminals 142 e-142 f is less than thevoltage at terminal 122 but greater than zero, and the voltage atterminals 142 a-142 d is less than zero. Furthermore, the voltage atterminals 140 g-140 h is greater than the voltage at terminal 122, thevoltage at terminals 140 e-140 f is greater than the voltage at terminal122 but less than the voltage at terminal 124, and the voltage atterminals 140 a-140 d is greater than the voltage at terminal 124.

In this configuration, arrangement 16 can receive energy from unit 15 ordevice 19 if unit 15 or device 19 are suitably electrically connectedwith any of terminals 142 e-142 h. Arrangement 16 can provide energy tounit 15 or device 19 if unit 15 or device 19 are suitably electricallyconnected to any of terminals 140 a-140 h or 142 a-142 d.

If arrangement 16 acts as a boost converter, i.e., switch 132 isdisabled, the voltage at terminals 142 g-142 h is less than the voltageat terminal 122, the voltage at terminals 142 e-142 f is less than thevoltage at terminal 122 but greater than zero, and the voltage atterminals 142 a-142 d is less than zero. Furthermore, the voltage atterminals 140 g-140 h is greater than the voltage at terminal 122, thevoltage at terminals 140 e-140 f is greater than the voltage at terminal122 but less than the voltage at terminal 124, and the voltage atterminals 140 a-140 d is greater than the voltage at terminal 124.

In this configuration, arrangement 16 can receive energy from unit 15 ordevice 19 if unit 15 or device 19 are suitably electrically connectedwith any of terminals 142 e-142 h. Arrangement 16 can provide energy tounit 15 or device 19 if unit 15 or device 19 are suitably electricallyconnected to any of terminals 140 a-140 h or 142 a-142 d.

FIG. 9 shows an embodiment of arrangement 16. This embodiment includescapacitors 118, 120, terminals 122, 123, 124, node 126, diodes 128, 130,active switches 132, 134, and isolated transformer 144. In thisconfiguration, arrangement 16 can act as either a buck or boostconverter. If switch 132 is disabled, arrangement 16 acts, inter alia,as a boost converter. If switch 134 is disabled, arrangement 16 acts,inter alia, as a buck converter. The voltage at terminal 122 is lessthan the voltage at terminal 124 relative to terminal 123.

Isolated transformer 144 includes terminals 146, e.g., 146 a-146 j.Terminals 148, e.g., 148 a-148 j, and terminals 150, e.g., 150 a-150 j,are also shown. Other embodiments may have more or less terminals. Thediodes may or may not be included. The diodes may also be shorted.

In this configuration, arrangement 16 can provide energy to unit 15 ordevice 19 if unit 15 or device 19 are suitably electrically connected toany of terminals 150 a-150 j or 148 a-148 j.

While embodiments of the invention have been illustrated and described,it is not intended that these embodiments illustrate and describe allpossible forms of the invention. Rather, the words used in thespecification are words of description rather than limitation, and it isunderstood that various changes may be made without departing from thespirit and scope of the invention.

What is claimed:
 1. A vehicle power system comprising: an energy storageunit; an electric device; and a bi-directional DC-DC power converterelectrically connected between the unit and device, and including anon-isolated transformer having a primary winding, a plurality of inputports each tapping the primary winding such that each of the input portshas a DC voltage of a different magnitude, and a plurality of outputports each tapping the primary winding such that each of the outputports has a DC voltage of a different magnitude, wherein a polarity ofsome of the DC voltages of the input ports is different.
 2. The systemof claim 1, wherein the non-isolated transformer further has a secondarywinding and wherein the converter further includes at least one isolatedport tapping the secondary winding.
 3. The system of claim 1, whereinthe converter is a buck-boost converter.
 4. A power system comprising: abi-directional power converter including a non-isolated transformerhaving a primary winding, a plurality of input ports tapping the primarywinding such that the input ports have different DC voltages andpolarities, and a plurality of output ports tapping the primary windingsuch that the output ports have different DC voltages.
 5. The system ofclaim 4, wherein the non-isolated transformer further has a secondarywinding and wherein the converter further includes at least one isolatedport tapping the secondary winding.
 6. The system of claim 4, whereinthe converter is a buck-boost converter.
 7. A vehicle power systemcomprising: a bi-directional DC-DC buck-boost power converterelectrically connected between an energy storage unit and an electricdevice, and including a non-isolated transformer having a primarywinding and a plurality of ports tapping the primary winding such thatsome of the ports have different voltages with different polarities. 8.The system of claim 7, wherein the non-isolated transformer further hasa secondary winding and wherein the converter further includes at leastone isolated port tapping the secondary winding
 9. The system of claim7, wherein the some of the ports are input ports.